This Phase I/II open label study evaluated the long-term safety and efficacy of a ddI, FTC, and EFV regimen in pediatric patients. All study patients were either absolutely naive to antiretroviral therapy or had received less than or equal to 56 days perinatal prophylaxis or less than 7 days of cumulative antiretroviral therapy prior to study entry, and had a plasma screening plasma HIV-1 RNA levels >= 5000 copies/mL. This study was written to characterize the disposition of FTC, determine the PK data for ddI-EC QD, comparing the bio-availability of the enteric coated formulation with ddI pediatric powder for oral solution, and to provide insight into the age related pharmacokinetics differences observed in this and other studies.